1. Field of the Invention
The present invention relates to an exhaust gas purifying filter, and manufacturing method therefor, for collecting particulates contained in exhaust gas exhausted from an internal combustion engine so that the exhaust gas can be purified.
2. Description of the Related Art
Conventionally, there has been provided an exhaust gas purifying filter for collecting particulates contained in exhaust gas exhausted from an internal combustion engine so that the exhaust gas can be purified. For example, as shown in FIGS. 11 and 12, the exhaust gas purifying filter is composed of a honeycomb structure 90 having cells 92, and a plug member 94 is arranged at one end of each cell 92.
When the exhaust gas 4 is purified with the exhaust gas purifying filter 9 described above, as shown in FIG. 12, the exhaust gas 4 is introduced into each cell 92 from the opening portion 93 of the cell 92 arranged on one end face 991 of the exhaust gas purifying filter 9. The exhaust gas 4 introduced into the cell 92 passes through the bulkhead 91 and moves into the adjoining cell 92. At this time, particulates in the exhaust gas 4 are collected by the bulkhead 91, so that the exhaust gas 4 can be purified. For example, when a catalyst is held by the bulkhead 91, the thus collected particulates can be decomposed and removed by a catalytic reaction of the catalyst.
The purified exhaust gas 4 is exhausted from the opening portion 93 of the cell 92 arranged on the other end face 992 of the exhaust gas purifying filter 9.
In this way, the exhaust gas 4 can be purified by the exhaust gas purifying filter 9.
However, the following problems may be encountered in the above conventional exhaust gas purifying filter 9.
The aforementioned plug member 94 is arranged in one of the opening portions 93 of the cell 92. Usually, this plug member 94 has no particulate collecting function. For the above reasons, the portion of the plug member 94, that is, one end portion of the cell 92 cannot be effectively used as a filter. Accordingly, there is a possibility that the purifying efficiency of purifying the exhaust gas 4 is not sufficiently high.
Further, there is a possibility that the following problems may be encountered. Particulates are concentrated upon and accumulated in portions close to both end faces 991, 992 of the exhaust gas purifying filter 9, and the opening portion 93 of the cell 92 is clogged.
In order to solve the above problems, as shown in FIG. 13, there is disclosed a filter 8 in which the bulkhead 81 is deformed so as to close one end portion of the cell 82 (Published Japanese translations of PCT international publication No. 8-508199).
In this filter 8, one end portion of the cell 82 is blocked by the bulkhead 81 having a function of collecting particulates. Even at this one end portion of the cell 82, when the exhaust gas passes through the bulkhead 81, it is possible to purify the exhaust gas 4. Therefore, the purifying efficiency of purifying the exhaust gas 4 can be enhanced.
However, when the bulkhead 81 is deformed as described above, extrusion molding is conducted to form a honeycomb body, and then deforming is conducted on the dried honeycomb body. Accordingly, it is necessary to give a high intensity pushing force to the end portion of the bulkhead 81. For the above reasons, it is difficult to smoothly deform the bulkhead 81 into a desired profile.
Further, another method is disclosed in which the bulkhead 81 is soaked in a soaking liquid so that the bulkhead 81 can be easily deformed, and then the bulkhead 81 is pressed and deformed. However, this method is disadvantageous because it is necessary to newly provide a soaking process, and the soaking can be time-consuming. Therefore, the production efficiency is deteriorated.